Aminoguanidine is a raw material for synthesis of medicines, dyes, photographic chemicals, gunpowder, etc., and in particular, its anti-glycation effect is widely known in the field of medicines (see Non Patent Literature 1). As the anti-glycation effect of aminoguanidine have been found inhibition of the in vitro formation of AGEs, inhibition of the crosslinking or polymerization of a protein, and prophylaxis of nephropathy, retinopathy, and neuropathy and an effect of preventing the progression of diabetes complications in an animal model of diabetes (see Non Patent Literature 2).
In addition to the above applications, aminoguanidine has been recently found to be useful for an absorber for odor components of aldehydes, i.e., an aldehyde catcher (see Patent Literature 1) and has been used as an additive for rubbers (see Patent Literature 2). More and more diverse physical properties have been required for the application, and a compound alternative to conventional aminoguanidine is required to be provided.
Fillers are additives for rubbers to be mixed in a rubber for the purpose of reinforcement or bulking of the rubber, imparting a special function to the rubber, etc. Carbon black, a representative filler, not only contributes to enhancement of the physical properties (reinforcing effect), such as elastic modulus and breaking strength, of a rubber, but also has a function of imparting conductivity, etc.
To obtain a reinforcing effect for rubbers similar to carbon black and obtain a rubber composition having low heat build-up, i.e., low loss properties, a method of using an inorganic filler such as silica is known, and has been applied, for example, to rubber compositions for environmentally friendly, fuel-efficient tires, etc.
In an inorganic filler-blended rubber composition, an inorganic filler, especially hydrophilic silica having a silanol group on the surface, blended therein agglomerates in the rubber composition due to its low affinity for a rubber, which is hydrophobic. Thus, it is required to enhance the affinity of silica for a rubber to enhance the reinforcing capability of silica and obtain an effect of lowering heat build-up. Known examples of such methods include use of a synthetic rubber the affinity of which for inorganic fillers is enhanced through end group modification with a polar group (see Patent Literature 3) and use of a synthetic rubber the affinity of which for inorganic fillers is enhanced through copolymerization of a polar group-containing monomer (see Patent Literature 4). Known examples of methods for modifying a natural rubber to introduce a polar group include a method in which a natural rubber is oxidized and then modified with a hydrazide compound having a polar group (see Patent Literature 5) and a method in which a silane coupling agent is added to a rubber composition containing a modified natural rubber having a polar group introduced and silica to further enhance the dispersibility of the silica (see Patent Literature 6).